第二次作业：MySQL数据库及Java操作MySQL数据库

 把mysql与java连接的jar（mysql-connector-java-5.1.6-bin.jar）包导入工程.
package com.cn.edu;
      
    import java.beans.Statement;  
    import java.sql.Connection;  
    import java.sql.DriverManager;  
    import java.sql.PreparedStatement;  
    import java.sql.ResultSet;  
    import java.sql.SQLException;  
      
    public class helloworld {  
        private Connection conn = null;  
        PreparedStatement statement = null;  
      
        // connect to MySQL  
        void connSQL() {  
            String url = "jdbc:mysql://localhost:3306/hello?characterEncoding=UTF-8";  
            String username = "root";  
            String password = "root"; // 加载驱动程序以连接数据库   
            try {   
                Class.forName("com.mysql.jdbc.Driver" );   
                conn = DriverManager.getConnection( url,username, password );   
                }  
            //捕获加载驱动程序异常  
             catch ( ClassNotFoundException cnfex ) {  
                 System.err.println(  
                 "装载 JDBC/ODBC 驱动程序失败。" );  
                 cnfex.printStackTrace();   
             }   
             //捕获连接数据库异常  
             catch ( SQLException sqlex ) {  
                 System.err.println( "无法连接数据库" );  
                 sqlex.printStackTrace();   
             }  
        }  
      
        // disconnect to MySQL  
        void deconnSQL() {  
            try {  
                if (conn != null)  
                    conn.close();  
            } catch (Exception e) {  
                System.out.println("关闭数据库问题 ：");  
                e.printStackTrace();  
            }  
        }  
      
        // execute selection language  
        ResultSet selectSQL(String sql) {  
            ResultSet rs = null;  
            try {  
                statement = conn.prepareStatement(sql);  
                rs = statement.executeQuery(sql);  
            } catch (SQLException e) {  
                e.printStackTrace();  
            }  
            return rs;  
        }  
      
        // execute insertion language  
        boolean insertSQL(String sql) {  
            try {  
                statement = conn.prepareStatement(sql);  
                statement.executeUpdate();  
                return true;  
            } catch (SQLException e) {  
                System.out.println("插入数据库时出错：");  
                e.printStackTrace();  
            } catch (Exception e) {  
                System.out.println("插入时出错：");  
                e.printStackTrace();  
            }  
            return false;  
        }  
        //execute delete language  
        boolean deleteSQL(String sql) {  
            try {  
                statement = conn.prepareStatement(sql);  
                statement.executeUpdate();  
                return true;  
            } catch (SQLException e) {  
                System.out.println("插入数据库时出错：");  
                e.printStackTrace();  
            } catch (Exception e) {  
                System.out.println("插入时出错：");  
                e.printStackTrace();  
            }  
            return false;  
        }  
        //execute update language  
        boolean updateSQL(String sql) {  
            try {  
                statement = conn.prepareStatement(sql);  
                statement.executeUpdate();  
                return true;  
            } catch (SQLException e) {  
                System.out.println("插入数据库时出错：");  
                e.printStackTrace();  
            } catch (Exception e) {  
                System.out.println("插入时出错：");  
                e.printStackTrace();  
            }  
            return false;  
        }  
        // show data in ju_users  
        void layoutStyle2(ResultSet rs) {  
            System.out.println("-----------------");  
            System.out.println("执行结果如下所示:");  
            System.out.println("-----------------");  
            System.out.println(" 用户ID" + "/t/t" + "淘宝ID" + "/t/t" + "用户名"+ "/t/t" + "密码");  
            System.out.println("-----------------");  
            try {  
                while (rs.next()) {  
                    System.out.println(rs.getInt("ju_userID") + "/t/t"  
                            + rs.getString("taobaoID") + "/t/t"  
                            + rs.getString("ju_userName")  
                             + "/t/t"+ rs.getString("ju_userPWD"));  
                }  
            } catch (SQLException e) {  
                System.out.println("显示时数据库出错。");  
                e.printStackTrace();  
            } catch (Exception e) {  
                System.out.println("显示出错。");  
                e.printStackTrace();  
            }  
        }  
      
        public static void main(String args[]) {  
      
            helloworld h = new helloworld();  
            h.connSQL();  
            String s = "select * from ju_users";  
      
            String insert = "insert into ju_users(ju_userID,TaobaoID,ju_userName,ju_userPWD) values("+8329+","+34243+",'mm','789')";  
            String update = "update ju_users set ju_userPWD =123 where ju_userName= 'mm'";  
            String delete = "delete from ju_users where ju_userName= 'mm'";  
      
            if (h.insertSQL(insert) == true) {  
                System.out.println("insert successfully");  
                ResultSet resultSet = h.selectSQL(s);  
                h.layoutStyle2(resultSet);  
            }  
            if (h.updateSQL(update) == true) {  
                System.out.println("update successfully");  
                ResultSet resultSet = h.selectSQL(s);     
                h.layoutStyle2(resultSet);  
            }  
            if (h.insertSQL(delete) == true) {  
                System.out.println("delete successfully");  
                ResultSet resultSet = h.selectSQL(s);  
                h.layoutStyle2(resultSet);  
            }  
              
            h.deconnSQL();  
        }  
    }  

1、创建数据库

create databasecwq

go

2、连接数据库

use cwq

go

3、创建数据表

命令：create table <表名> ( <字段名1> <类型1> [,..<字段名n> <类型n>]);
建立一个名为Class的表

mysql> create table Class(
> id int(4) not null primary key auto_increment,
> name char(20) not null,
> sex int(4) not null default ‘0‘,
> degree double(16,2));

4、删除数据表

drop table cwq